The regulation of the immune response by T-suppressor (Ts) cells induced via the injection of antigen-modified self will be further studied. In particular, we will continue to establish Ts cell lines, somatic cell hybrids of Ts cells, or rad leukemia virus transformants of such cells. Ts lines with specificity for the TNP hapten, dextran, or the MOPC-104E idiotype will be cloned and analyzed in terms of the target cell population, specificity, and restriction. We will also attempt to establish both plaque and ELISA assays for the specific and nonspecific products of these cells. Recently, we have begun to analyze the role of antigen-presenting (accessory cells) in stimulating either T helper versus suppressor cells. We will also determine the mechanism by which allogeneic hybrid myeloma cells provide for augmented survival against a normally lethal parental-tumor challenge. The role of suppressor cells recognizing modified self will be evaluated in this context. (LB)